1. Field of the Invention
The present invention concerns a new elastic membrane press filter. It also concerns a filtration method using said press filter.
The present invention concerns in particular an elastic membrane press filter, in particular a mash filter, made up of filter elements each comprising a frame and a filtration plate carrying a filtration member for forming a filtration chamber, a lower feed pipe passing through each filter element with inlet pipes and inlet pipe orifices, enabling the liquid to be filtered to flow from said lower feed pipe into said filtration chambers.
2. Description of the Prior Art
Elastic membrane press filters are well known and widely used. Each filter element comprises an elastic member which separates two chambers, said filtration chamber which receives the liquid to be filtered and containing solid materials and an air chamber which delimits a space into which air can be fed. By pressurizing the air the membrane is moved towards said filtration member, so compressing the solid material contained in the liquid to be filtered into the form of a "cake".
These press filter elements have various drawbacks, however. For example, when the elastic membrane starts to move towards the filtration member, the entry of the liquid to be filtered is not interrupted quickly, which causes a quantity of the liquid to be returned to the feed pipe. This can lead to soiling of the inlet pipe orifice. These phenomena are more marked if the inlet pipe orifice is closed very tardily.
A main object of the invention is to optimize the filter capacity of all the elements constituting the press filter independently of the distance of the filter elements from the place at which the products to be filtered enter the lower feed pipe.
Another object of the invention is to remedy most of the above drawbacks, especially those connected with soiling of the feed pipe orifice.